Original Articles

Computational Fluid Dynamic Analysis to Prevent Aortic Root and Valve Clots during Left Ventricular Assist Device Support

Address correspondence to: Michael Poullis, BSc(Hons), MBBS, MIEEE, FRCS(Cth), Consultant Cardiothoracic Surgeon, Liverpool Heart and Chest Hospital, Thomas Drive, Liverpool, L14 3PE, UK. E-mail: mike.poullis@lhch.nhs.uk

Received: 21 March 2012
Accepted: 20 September 2012

Abstract

Aortic root and valve clots are rare but well described in patients on maximal left ventricular assist device (LVAD) support. We performed a theoretical analysis using computational fluid dynamic analyses in two dimensions to try and ascertain if inflow cannula design/orientation/placement affect aortic root flow dynamics. Two-dimensional computational fluid dynamics using easy CFD-G was performed. The effect of a curved inflow cannula, a straight cannula, and one with a hole in the outer curve was analyzed. In addition, the effect of inflow conduit angulation on the ascending aorta was studied. Computational fluid dynamic (CFD) analysis predicts that stagnant blood exists in the aortic root when little or no cardiac ejection is taking place. Coronary flow is too small to affect the root flow streamlines. A hole on the root side of a curved inflow aortic cannula increases the flow in the aortic root and may decrease the incidence of root and valve thrombosis. The angle of the inflow conduit attachment to the ascending aorta was also found to be crucial with regard to aortic root blood stasis. In addition, a baffle at the tip of the inflow cannula may prove to be beneficial. Theoretical analysis using the technique of CFD predicts that inflow cannula position and design may affect the incidence of aortic root thrombosis during LVAD support when minimal cardiac ejection is occurring.